ketan badgujar research scholar ee, iit bombayfclab/fem/femm_tutorial_2... · 2017. 12. 11. ·...
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Force on a plunger due to magnetic field in a nonlinear solenoid
Ketan Badgujar
Research Scholar
EE, IIT Bombay
IDLAB, IIT Bomaby
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Presentation Layout
Problem Definition
Geometry
Solution and post processing
Step:1
Step:2
Step:3
Step:4
Discritization and applying boundary conditions
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Problem Definition
Tutorial 2.pdfTutorial 2.pdf
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File-> New-> Magnetics problem-> click on `OK’
Draw the given transformer diagram-
• Click on (operate on nodes)-> left click on the screen -> right
click on the node (node becomes red > press Tab key-> enter the
new node location point-> click `OK’ similarly for all the points
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•Geometry
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x y x y
0 0 0 0.2
0.14 0 0 0.22
0.14 0.30 0 0.28
0 0.30 0.12 0.28
0 0.02 0.08 0.24
0.042 0.04 0.042 0.24
0.12 0.04 0.042 0.22
0.042 0.08 0.04 0.2
0.08 0.08 0.04 0.02
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•Co-ordinates
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• Click on (operate on segments) -> left click on first node (node becomes red)-> left click on the second node (now both node are connected through a line)
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Operate on segments
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• Click on (operate on block labels)-> left click on the each area once
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•Operate on blocks
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• Click on “Problem” from FEMM main menu-
• Click on ‘OK’
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Problem type and length units
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• Click on “Properties”->”Materials”-> Add property
• Set properties for air and coil as shown in figure
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Material properties
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• For, core & plunger “Properties”->”Materials”-> Add property ->B-H Curve (Nonlinear BH-Curve)->Click on “Edit B-H Curve”-> click on “OK”
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Material properties
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• Click on “Properties”->”Boundary”->Add property -> click on ‘OK
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Boundary property
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• Click on (operate on block labels)-> Right click on a block (point of block becomes red)-> press the space key
• Click on ‘OK’ similarly for all the blocks
• Here we are defining meshing size to each material
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• Click on (operate on segments)-> Right click on the one of the four outer most lines (Line becomes red)-> press space key
• Click on ‘OK’ similarly for three remaining lines
• In this step we are assigning boundary conditions
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Set boundary conditions
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• Click on -> click on ‘OK’
• Above button runs mesh generator
• This step creates mesh for the given geometry
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Meshing
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• Click on ‘hand crank’ icon , it executes the solver
• Now click on . This is ‘glass’ button to display the results in post processing window
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Output
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• Click on -> Left click on the plunger (area becomes colored)
• Click on ->
• Click on ‘OK’
• Force = 363 N
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Post processing
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•Density plot
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The core is assumed to have infinite permeability requiring no magnetizing mmf
Let, Ampere current density (ATD) = Current density (J)
Ampere current ( AT ) = 6080
Hg = AT/g =304000
where, g air gap distance
Bg = µ0Hg = 0.382
where, A=area of cross section of coil
fe = 261 N
The difference in numerical and analytical solution is due to fringing
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Analytical solution
2
g
e
0
B1f = ×A
2 μ
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Thank you
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